Process for the production of gamma quinacridone
AssigneeAllied Chemical Corporation
InventorRobert Jarl North
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Abstract
A method is provided for the direct production of the gamma crystalline phase of quinacridone. The method comprises ring closing a mixture of dianilinoterephthalic acid and 10 - 20 weight percent of di-(ortho substituted) anilinoterephthalic acid in polyphosphoric acid and thereafter diluting the product with water.
Claims3
A process for producing gamma quinacridone which comprises heating, between 80.degree. and 120.degree.C, a mixture of dianilinoterephthalic acid containing 10-20 weight percent of di-(ortho substituted) anilinoterephthalic acid in the presence of polyphosphoric acid and thereafter diluting the reaction mixture with water and recovering the precipitated gamma quinacridone, wherein the substituents on the di-(ortho substituted) anilinoterephthalic acid are halogens, alkyl containing 1 - 4 carbon atoms, alkoxy containing 1 - 4 carbon atoms, halogenated alkyl containing 1 - 4 carbon atoms or carboalkoxy containing 1 - 4 carbon atoms.
Dependencies are inferred from the claim text.